Disable ActionView::Template finalizers in test environment

actionview/CHANGELOG.md

@@ -1,3 +1,12 @@
+*   Disable `ActionView::Template` finalizers in test environment
+
+    Template finalization can be expensive in large view test suites.
+    Add a configuration option,
+    `action_view.finalize_compiled_template_methods`, and turn it off in
+    the test environment.
+
+    *Simon Coffey*
+
 *   Extract the `confirm` call in its own, overridable method in `rails_ujs`.
     Example :
         Rails.confirm = function(message, element) {

actionview/lib/action_view/railtie.rb

@@ -10,6 +10,7 @@ class Railtie < Rails::Engine # :nodoc:
     config.action_view.embed_authenticity_token_in_remote_forms = nil
     config.action_view.debug_missing_translation = true
     config.action_view.default_enforce_utf8 = nil
+    config.action_view.finalize_compiled_template_methods = true
 
     config.eager_load_namespaces << ActionView
 
@@ -45,6 +46,13 @@ class Railtie < Rails::Engine # :nodoc:
       end
     end
 
+    initializer "action_view.finalize_compiled_template_methods" do |app|
+      ActiveSupport.on_load(:action_view) do
+        ActionView::Template.finalize_compiled_template_methods =
+          app.config.action_view.delete(:finalize_compiled_template_methods)
+      end
+    end
+
     initializer "action_view.logger" do
       ActiveSupport.on_load(:action_view) { self.logger ||= Rails.logger }
     end

actionview/lib/action_view/template.rb

@@ -9,6 +9,9 @@ module ActionView
   class Template
     extend ActiveSupport::Autoload
 
+    mattr_accessor :finalize_compiled_template_methods
+    self.finalize_compiled_template_methods = true
+
     # === Encodings in ActionView::Template
     #
     # ActionView::Template is one of a few sources of potential
@@ -307,7 +310,9 @@ def #{method_name}(local_assigns, output_buffer)
         end
 
         mod.module_eval(source, identifier, 0)
-        ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
+        if finalize_compiled_template_methods
+          ObjectSpace.define_finalizer(self, Finalizer[method_name, mod])
+        end
       end
 
       def handle_render_error(view, e)

guides/source/configuring.md

@@ -600,6 +600,13 @@ Defaults to `'signed cookie'`.
 
 * `config.action_view.default_enforce_utf8` determines whether forms are generated with a hidden tag that forces older versions of Internet Explorer to submit forms encoded in UTF-8. This defaults to `false`.
 
+* `config.action_view.finalize_compiled_template_methods` determines
+  whether the methods on `ActionView::CompiledTemplates` that templates
+  compile themselves to are removed when template instances are
+  destroyed by the garbage collector. This helps prevent memory leaks in
+  development mode, but for large test suites, disabling this option in
+  the test environment can improve performance. This defaults to `true`.
+
 ### Configuring Action Mailer
 
 There are a number of settings available on `config.action_mailer`:

railties/lib/rails/generators/rails/app/templates/config/environments/test.rb.tt

@@ -47,4 +47,7 @@ Rails.application.configure do
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+
+  # Prevent expensive template finalization at end of test suite runs.
+  config.action_view.finalize_compiled_template_methods = false
 end